Pioneering link to Gotland

Gotland was originally self-sufficient in terms of electrical energy, based on fossil fueled generation. A thermal power station in Slite catered for the needs of the entire island, but production costs were relatively high and tariffs were double those on the Swedish mainland. This made it expensive to run industries on Gotland and there were increasing problems with unemployment and depopulation. 

In order to break this negative trend the Swedish parliament decided in 1950 to finance a power transmission link from the mainland to the island. The project of establishing the first submarine HVDC (high-voltage direct current) link was ordered by the state-owned utility Vattenfall. 

This link was designed to satisfy a greater demand for electricity and at the same time reduce the tariffs on the island in order to simplify life for businesses and islanders. The transmission used HVDC technology due to the long distance, about 96 km, across the sea. 

The pioneering HVDC transmission cable system was laid in 1953, between Västervik on the Swedish mainland and Ygne, 10 km south of Visby on Gotland, and operation commenced in 1954. The 96 km long cable system used MI (mass-impregnated) technology. The link then had a rated voltage of 100 kV (kilovolt) and a transmission capacity of 20 MW (megawatt). 

When the converter stations were upgraded and the voltage was raised to 150 kV in the 1970s, the cable system was used with a new transmission capacity of 30 MW. In the next decade, further submarine cables were added and others were taken out of service. Nowadays, the systems Gotland 2 and 3, who can also be run independently, work as a bipolar link with a total capacity of 260 MW.   

Being the first link with commercial mercury arc HVDC converter stations and HVDC submarine cable system, the Gotland link was awarded the very first IEEE Milestone in Sweden in 2017. It is considered a key historical achievement by the IEEE (Institute of Electrical and Electronics Engineers).

Cable system design and engineering, including one 96 km long submarine MI cable as well as 7 km of DC overhead line

96 km

100 kV system with a 20 MW rating developed to a 150 kV system with a 260 MW rating

1953 - 1954 and additions in the 1980's

Vattenfall

Baltic Sea, Sweden

 

 

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